Learn Library · Trouble-Code Guides
A trouble code names the test that failed — not the part to replace. These guides walk through the codes we see most at our Denton counter: what each one actually measures, the inexpensive causes worth ruling out first, and how to tell when the expensive part really is the fix.
The Code Series
If the light is flashing, start with the first guide — it's the one distinction that can't wait. Otherwise, find your code below.
The most important distinction on your dash — solid means soon, flashing means stop. What each state tells you and what to do next.
Why the code isn't always the catalytic converter — and the cheaper upstream causes to rule out before anyone condemns the cat.
The gateway code — it means the transmission computer has its own codes to pull before anyone guesses at a fix.
Often a range-sensor or shift-linkage adjustment — not the transmission itself. What the sensor does and how the fix escalates.
What the converter-clutch code means — and why a fluid-first check is the honest starting point before anyone says converter.
Why 'it drives normal' and 'nothing's wrong' aren't the same thing — and how long you can reasonably wait.
The multi-cylinder misfire code — plugs, coils, fuel, or vacuum, and how the real culprit gets isolated.
Denton, TX · Since 1995
A guide tells you what the code means; a diagnosis tells you what your car needs. Bring it to the shop that has run down check-engine lights in Denton since 1995 — you'll get the actual cause in plain English and a written estimate before any work begins.
